Medical male circumcision (MMC) reduces HIV acquisition in men, and viral STIs in men and women. However, uptake of MMC in many African countries is less than expected and has disproportionately been among younger, lower risk men. There is an urgent need for implementation science incorporating qualitative/quantitative mixed methods research to increase the demand for MMC, particularly among higher risk men; to increase the efficiency of MMC services using MC devices, task shifting/sharing and mobile MMC camps; and to conduct population-level monitoring of coverage and impact. At the basic science level, foreskins collected during MC provide unique access to genital mucosa for study of the virologic, immunologic and host genetic factors associated with vulnerability to or protection from HIV, with implications for HIV prevention. The Rakai Health Sciences Program (RHSP) and Makerere University School of Public Health (MakSPH) in Uganda have collaborated with Johns Hopkins University (JHU) for over 20 years. We conducted two trials of MMC, post-trial surveillance, evaluation of MMC services, and assessment of MMC procedures, including new MMC devices. We have also collaborated on immunologic and virologic studies of foreskin tissues and the genital microbiome. The collaboration has trained over 50 degree and non-degree students via Fogarty International Center (FIC) awards. We propose to continue these training efforts and to provide research opportunities and career development for Ugandan scientists focusing on MMC related research, both because MMC is vital to HIV prevention, and because MMC-related research provides an opportunity for a wide range of synergistic and interdisciplinary studies. Specifically, at JHU we propose to train one PhD candidate in genital immunology, virology and molecular microbiology, and 5 MPH/MHS candidates in implementation science, epidemiology and biostatistics, program evaluation and mixed methods research. We will train 2 doctoral students at MakSPH, using an established sandwich PhD which allows short-term trainees to come to JHU for advanced courses and mentoring. In Uganda, we will support 5 Masters and 3 Bachelors degree trainees, and 18 diploma/certificate trainees at MakSPH and other Ugandan universities. The U.S. Program Director (PD) Dr. Ronald Gray, Professor of Epidemiology at the JHU and the Ugandan Key Foreign Collaborator is Dr. David Serwadda, Professor, at MakSPH. Training will be overseen by Training Advisory Committees in Uganda and the US. RHSP/MakSPH will provide access to the Rakai research field site for experiential training, data and samples for training-related research, and a rich stable environment for career development. The program builds on prior training and research to ensure the long-term sustainability and leadership of RHSP and MakSPH as world class HIV research institutions.